Dental matrix clamp



Jan. 27, 1970 R. 1.. NEWMAN 3,491,447

DENTAL MATRIX CLAMP Filed Sept. 3, l968 United States Patent Office 3,491,447 Patented Jan. 27, 1970 3,491,447 DENTAL MATRIX CLAMP Roy L. Newman, 1023 Lundvall, Rockford, Ill. 61107 Continuation-impart of application Ser. No. 538,459, Mar. 23, 1966. This application Sept. 3, 1968, Ser. No. 757,013

Int. Cl. A61c /12 US. Cl. 32-63 2 Claims ABSTRACT OF THE DISCLOSURE The clamp has a laterally disposed pivot so a matrix strip can be passed through its central portion. The nose of the clamp is concave in shape to hold the matrix strip closely adjacent the tooth surface.

CROSS-REFERENCE This is a continuation-in-part application of application Ser. No. 538,459, filed Mar. 23, 1966 and now Patent No. 3,421,222.

BACKGROUND The invention pertains to the field of dentistry; particularly to a dental instrument for clamping a matrix strip.

Many types of dental matrix clamps have been used by dentists. In some however, the matrix strip is not easily inserted. In others, the clamp does not hold the lateral edges of the matrix strip closely adjacent the tooth. This latter deficiency is particularly critical when the matrix strip is being used in the method disclosed and claimed in the aforementioned parent application. Looseness at the edges of the strip allows oozing of the filling material. In the past, this excess material was removed by chipping or grinding. As harder and more adhesive materials have developed, removal of excess filling material has become more difficult. It is preferable, therefore, to hold the lateral edges of the matrix strip closely adjacent the tooth to minimize such problems.

SUMMARY The present invention relates to a dental matrix clamp for use in securing a matrix strip.

It is a general object of this invention to provide a unique clamping device for holding a dental matrix strip generally contiguous to a tooth.

Another object is to provide a dental matrix clamp which aids in procuring substantially perfect marginal adaption of the filling material on all portions of the cavity margins.

Still another object of the present. invention is to provide a dental matrix clamp which holds the lateral edges of the matrix strip closely adjacent the tooth.

Yet another object is to provide a dental matrix clamp which is so arranged that a looped matrix strip is easily inserted into the clamp These, and other objects and advantages of the invention, will become apparent as the apparatus becomes better understood by reference to the following description taken in conjunction with the drawings.

FIGURE 1 is a view, in part perspective and in part diagrammatic, showing the dental matrix clamp of the present invention in use for clamping a dental matrix strip;

FIG. 2 is a partial sectional view taken generally along line 22 of FIG. 1;

FIG. 3 is a large-scale top plan view of a dental matrix clamp constructed in accordance with the present invention;

FIG. 4 is a front view of the matrix clamp of FIG. 3;

FIG. 5 is a partial end view taken along line 55 of FIG. 4; 4 FIG. -6 is an end view as seen from the right of FIG.

FIG. 7 is a perspective view of the dental matrix clamp.

The aforementioned parent application, now Patent No. 3,421,222, disclosed a method and apparatus for filling dental cavities. FIGURE 1 illustrates that method being performed. A plurality of anterior teeth 20-22 are illustrated, with a cavity 21a shown in tooth 21. The cavity 21a may be prepared for filling in the usual manner as, for example, undercutting the sides in a generally keyshape (FIG. 2). The cavity preparation may include i lining the cavity with a cement, a primer, or a pulp-clapping composition. The preparation may also include moisture exclusion by physical or chemical means to exclude moisture from the cavity during placement of the filling material. In accordance with the method of the parent application, following the preparation of the cavity, a matrix strip is secured in position over the cavity. The cavity is then filled through an opening in the matrix strip, as by inserting a tubular barrel of a filling material dispenser 70 through the opening, and dispensing a flowable filling material through the barrel.

Prior to positioning, the strip may be pulled over the rim of a dentists mirror or any round edge to concave the surface and avoid cupping the filling. This is particularly applicable to large cavities. The opening in matrix 32 is positioned over the cavity 21a and the strip is doubled upon itself to provide a loop extending around the tooth 21 with the end portions of the matrix strip in juxtaposition. The dentist then pulls on the end portions to tighten the central portion of the strip against the tooth and clamps the end portions in an area adjacent the tooth to hold the central position tightly against the tooth. The clamping is advantageously performed by the dental matrix clamp of the present invention, generally designated 61. It is to be understood that the dental matrix clamp may be utilized with a conventional matrix strip in the conventional manner, in addition to the above described use.

A preferred matrix clamp 61 is illustrated in detail in FIGS. 3-7. Preferably, clamp 61 has a height slightly greater than the width of the matrix strip 32, and a length less than the length of the looped matrix strip so that the strip extends through the clamp (see FIG. 1). The clamp comprises elongate body elements or members 62, 63 having inwardly tapered portions 62a, 63a and opposed nose portions 62b, 63b. Each nose portion is provided with a plurality of sharp teeth 64 arranged to interfit with teeth of the opposite nose portion. The outer surface of nose portions 62b, 63b, is preferably concave, as shown in FIG. 13, to generally conform to the labial surface of a typical anterior tooth. Because of the shape of a typical tooth, its circumference at one or both lateral edges of the matrix strip 32 is usually less than at the middle. This may cause a gap at the edge and allow the filling material to ooze. The concave nose portion, when opened, allows the teeth to engage the strip so that the midportion has a greater loop circumference than the lateral edges. When allowed to close, this pulls the lateral edges into tight engagement with the tooth. The sharp teeth 64 in the clamp also assure that this tightness is accomplished. In this manner, when clamped on a matrix strip, the strip is gripped closely adjacent the tooth over its entire width.

Adjacent one longitudinal side of the clamp are arms 65, 66 mounted on members 62, 63, respectively. The arms are pivotally connected by means of a fastener 67 and arm 65 conveniently has a rearward extension for mounting a spring 68, as by fastener 69. The rearward extension of arm 65 has an edge 65a defining a shoulder which engages the inner surfaceflof the lower extremity of member 63. This engagement limits the opening of the clamp in such a manner that both the teeth 64 and the rear end of members 62 and 6 3 are spaced from each other. This provides an open area into which the matrix strip can be easily inserted as hereafter discussed. The spring 68 is advantageously U-shaped and has its legs extending sidewardly and upwardly into engagement with the inner surface of members 52, 63. It will be noted that this arrangement of arms 65, 66, and spring 68 is dispose-:1 generally at a side of the members 62, 63 thereby leaving the area therebetween substantially open for reception of a matrix strip. After the matrix is looped amend a tooth and its end portions placed in juxtaposition, the clamp is; easily opened and slipped over the matrix strip from the side opposite arms 65, 66'. With this arrangement there is no interference 'with the'insertion' of the matrix strip.

It is new deemed obvious that the present invention provides a dental matrix clamp into which a matrix strip can be easily inserted and which holds the strip closely adjacentthe labial surface of an anterior tooth across the entire width of the strip. 1

What is claimed is: 1. A, dental matrix elamp for securing an elongate matrix strip around an anterior tooth wherein the matrix strip has a central portion wrapped around the tooth and end portions in juxtaposition and extending outwardly from;;the tooth in a longitudinal direction, the dental matrix clamp comprising: e

first and second longitudinal body elements spaced for receiving the end portions of the matrix strip in the area therebetween; each body element having front 4 and rear ends, a width not more than slightly greater than the Width of the matrix strip, and a length less than the length of the looped matrix strip; a gripping portion at the front end of each body ele ment extending toward the other gripping portion for gripping the matrix strip therebetween;

means attached to the bpdy elements intermediate the ends thereof and at only one lateral side thereof for pivotally connecting the body, elements and leaving the matrix strip area and the other lateral side open for entry of the matrix strip from the other lateral side into the matrix strip area and including a first arm attached to the first body element, a second arm attached to the second body element, and a fastener pivotally connecting the arms; one of said arms having a shoulder for engaging the other body element when the clamp is an open position with all portions of the body elements and the gripping portions spaced from each other for reception of the matrix strip therebetwen; and a spring 'having an intermediate portion disposed laterally of said matrix strip area and mounted on one of the arms, and the spring having end portions each operatively connected to a respective body element for resiliently urging the gripping portions toward each other; whereby the rear ends of the body elements may be squeezed to separate the gripping portions, the matrix strip inserted between the gripping portions and between the body elements from said other lateral side with the ends of the matrix strip disposed rearwardly of the rear ends of the body elements, the ends of the matrix strip may be pulled to tighten the matrix strip around the tooth, and the rear ends of the body elements released to clamp the matrix strip in place. 2. A dental matrix clamp as set forth in claim 1 wherein the gripping portions have a plurality of interfitting teeth and a concave surface at the front end approximately complementary to an anterior surface of the' anterior tooth, whereby the matrix strip may'be gripped closely adiacent said anterior surface. Y

e a ileferenc es Cited W UNITED STATES PATENTS 1,958,667 5/1934 Howe 32-63 2,267,836 12/1941 Parkin 32-63 3,131,449 5/1964 Itda 24137.5

ROBERT PESHQCK, Primary Examiner 

